1. Field of the Invention:
This invention relates to an arrangement for displaying the operating state of a booster circuit of a flash device for a camera and more particularly and to an improvement on such arrangement which is capable of making a stable display.
2. Description of the Prior Art:
Heretofore, a conventional arrangement for displaying the operating state of a booster circuit of an electronic flash device for a camera has been arranged to obtain a supply of power for a display element 61 thereof directly from a power source battery 62, as shown in FIG. 1 of the accompanying drawings. However, during a period from the start of operation of the booster circuit and to the end of a charging process on a main capacitor 63, the voltage of the power source battery greatly varies causing the display brightness of the display element 61 to fluctuate.
This is due to a current of several amperes being drawn out from the battery 62 during the initial stages of operation of the booster circuit to resulting in an extremely great drop of voltage between the terminals of the battery 62, as shown in FIG. 2. When the battery 62 has been consumed to a certain degree, the brightness of the display element 61 drops to hindering ready confirmation of the operating stage of the booster circuit. Further, even in the case where the booster circuit is in an inoperative state due to some malfunction thereof, erroneous closing of a power supply switch 64 sometimes has occasioned the display element 61 to light up.
Meanwhile, if the resistance value of a resistor 65 is arranged to be small for the purpose of making the display element 61 sufficiently bright from the beginning of the operation of the booster circuit, the consumption of current by the display element 61 increases as the voltage between the terminals of the battery 62 recovers, accordingly as the charging voltage of the main capacitor 63 rises. That arrangement thus accelerates the consumption of the battery 62.